Variable pitch storage shelves

ABSTRACT

The present invention generally comprises a container storage system for efficiently storing large capacity and small capacity containers or FOUPs. In one embodiment, each storage location within the stocker comprises a pair of spaced apart supports. A large capacity container or a small capacity container may be seated in any storage location. The storage locations are arranged within the stocker to minimize the amount of empty space between the supports of a storage location and a container seated in an adjacent storage location. In one embodiment, the vertical pitch between supports of adjacent storage locations is less than the height of a large capacity FOUP container shell. Thus, when a FOUP is seated in a storage location, its container shell extends between the supports of the storage location located directly above.

FIELD OF THE INVENTION

The present invention generally comprises a container storage device for simultaneously storing multiple containers of different dimensions in an efficient manner. More specifically, the present invention comprises a stocker for efficiently storing a plurality of Front Opening Unified Pods (FOUPs), or other containers with a mechanically openable door, that have varying dimensions.

BACKGROUND OF THE INVENTION

FIGS. 1-2 each illustrate a conventional stocker 10 for storing containers in a fabrication facility. FIG. 1 illustrates a conventional stocker 10 storing multiple FOUPs 2. A conventional FOUP 2 comprises (i) a pod shell 4, with a front opening 3, for isolating one or more wafers, (ii) a pod door 9 that mechanically couples to the front opening 3, (iii) a support plate 12 secured to the bottom of the FOUP shell 4 (or an integral part of the FOUP shell), and includes for example, three corresponding kinematic grooves (not shown) for seating over three corresponding kinematic pins located on a support surface (e.g., stocker shelf, load port kinematic plate, etc.), (iv) a top handle 6, and (v) a pair of side handles 8. Stockers 10 also store open cassettes, reticle containers and any other article storage container known within the art.

The stocker 10 shown in FIG. 1 includes, among other things, multiple storage shelves 12. A storage shelf 12 may comprise any support. Each FOUP 2 is seated on a storage shelf 12. The FIG. 1 embodiment illustrates that the shelves 12 are spaced a distance d1 apart. The distance d1 also allows for a clearance d2 between a storage shelf 12 and the top of a FOUP 2 located directly beneath the shelf 12. The clearance d2 provides space for a transfer mechanism (e.g., robotic arm mechanism) to, for example, grab a FOUP 2 by the FOUP's top handle 6 and lift the FOUP 2 off the shelf 12. It is also known within the semiconductor industry to engage a FOUP and lift the FOUP off a shelf by the FOUPs bottom plate.

Each shelf 12 may extend under any portion of the FOUP 2 as long as the shelf 12 adequately supports the FOUP 2. For example, each shelf 12 may comprise an area substantially equal to the bottom surface of the FOUP 2. Or the shelf 12 may comprise an area less than the area of the FOUP's bottom surface, as long as the shelf 12 may adequately support the FOUP 2 (e.g., the FOUP 2 will not tip over, wobble, etc. on the shelf 12). Each shelf 12 may also comprise a 3-point support fork or any other support structure known within the art.

FIG. 2 illustrates a conventional stocker 10 storing varying capacity FOUPs. The stocker 10 in FIG. 2 is storing large-capacity FOUPs 2 (e.g., a FOUP that stores up to 25 wafers) and small-capacity FOUPs 20 (e.g., a FOUP that stores less than 25 wafers). The stocker 10 may store any size FOUP or container. FIG. 2 demonstrates the inefficient result of storing small-capacity FOUPs 20 in a conventional stocker 10. As shown in FIG. 2, a large gap or distance d3 exists between the bottom of a shelf 12 and the top of a small capacity FOUP 20 stored on the next shelf 12 below. A minimum gap (e.g., distance d2) preferably exists between each shelf 12 and the top of a FOUP stored directly beneath on the next shelf 12 below so that a robotic arm, for example, may access the top handle 6 of a FOUP. The difference between the distance d3 and the distance d2 is wasted space, and cannot be avoided when storing small-capacity FOUPs 20 in a conventional stocker 10. The shelves 12 must comprise an evenly spaced arrangement (e.g., shelves are spaced a vertical distance d1 apart) to accommodate large-capacity FOUPs 2.

Thus, an improved stocker for simultaneously storing both small-capacity FOUPs 20 and large-capacity FOUPs 2 is needed in the industry. The present invention provides such a stocker.

SUMMARY OF THE INVENTION

One aspect of the present invention is to provide a container storage system that may simultaneously store both large-capacity containers and small-capacity containers in an efficient manner. In one embodiment, a small-capacity container comprises a FOUP for storing less than twenty-five semiconductor wafers and a large-capacity container comprises a conventional FOUP for storing up to twenty-five semiconductor wafers or more. The container storage system may store a small capacity or large capacity FOUP in any of the storage locations.

Another aspect of the present invention is to provide a container storage system having storage locations with standardized supports. In one embodiment, each storage location comprises a pair of supports. Each pair of supports are preferably separated by a distance greater that the width of the large-capacity FOUP shell. Even though the vertical pitch between the supports of adjacent storage locations is less than the height of a large capacity FOUP shell, a large-capacity FOUP may be stored in any storage location. The large capacity FOUP shell, when the large capacity FOUP is seated on a pair of supports, extends between the pair of supports located directly above. The pair of supports do not have to adjust to accommodate the large capacity FOUP.

Yet another aspect of the present invention is to provide a container storage system with storage locations that align and/or include registration features to ensure that each container is properly seated within the storage location. In one embodiment, each support within the storage location includes at least one registration feature, such as a kinematic pin or other location element, that registers with a bottom plate or flange of the FOUP. In another embodiment, each support includes a side wall to prevent the large capacity FOUP from moving laterally while seated on the supports.

Still another aspect of the present invention is to provide a container storage system that provides safety features to ensure that containers do not contact each other during transport and handling within the storage system. In one embodiment, at least one support in each storage location includes a sensor to detect whether a FOUP is seated within the storage location. The sensor prevents a transport mechanism from attempting to deliver a container to an already occupied storage location.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a schematic view of a conventional stocker, according to the prior art;

FIG. 2 provides a schematic view of the conventional stocker shown in FIG. 1, storing containers having different storage capacities;

FIG. 3 provides a schematic view of an embodiment of a stocker or storage device, according to the present invention

FIGS. 4A-4B provide plan and front views of an embodiment of a small capacity container stored in the stocker or storage device shown in FIG. 3;

FIGS. 5A-5B provide plan and front views of an embodiment of a large capacity container stored in the stocker or storage device shown in FIG. 3; and

FIGS. 6A-6B provide plan and front views of another embodiment of a workpiece container seated in a storage location

DETAILED DESCRIPTION OF THE INVENTION

Semiconductor Equipment and Materials International (SEMI) has created standards for semiconductor wafer manufacturing equipment (see http://www.semi.org). The SEMI Standards govern acceptable tolerances and interfaces for semiconductor manufacturing equipment. The inventions described herein are not limited to semiconductor manufacturing equipment for handling FOUPs or other types of containers.

By way of example only, the various embodiments of the present invention may also be used and/or adapted for systems handling SMIF pods, reticle containers, flat panel display transport devices, or any other container or processing tool. Container is defined as any type of structure for supporting an article including, but not limited to, a semiconductor substrate. By way of example only, a container includes a structure that comprises an open volume whereby the article can be accessed (e.g., FPD transport) or a container having a mechanically openable door (e.g., bottom opening SMIF pod and FOUP). For purposes of describing this invention, however, only FOUPs will be referenced herein.

FIGS. 3-5 describe various aspects if the present invention. For purposes of describing various aspects of the present invention, the container storage system is described herein in conjunction with a stocker. However, it is understood that the present invention also applies to other container storage systems such as, but not limited to, tool proximity buffers and other storage devices used within the semiconductor industry.

FIG. 3 illustrates a stocker 100. The stocker 100 includes multiple storage locations, each comprising a pair or set of support structures or bars 101. Each FOUP, whether it is a large capacity FOUP 2 or a small capacity FOUP 20, is supported by the pair or set of support structures 101.

The stocker 100 is described throughout in operation with a small capacity FOUP 20 and a large capacity FOUP 2 each having a bottom plate 32 and 12, respectively (see FIGS. 4-5). The bottom plate may be integrally formed with the container shell or comprise a separate structure that is secured to the container shell. The bottom plate may also be referred to as a flange. It is within the scope and spirit of the invention for a container to include other types of flanges. A flange may comprise any structure or feature, secured to or extending from the container shell, that mates with the supports in the storage location for supporting the container while the container is seated in a storage location. A flange may extend from the container shell at any elevation along the container shell (e.g., extend from the top of the container shell, extend from the middle of the container shell, comprise the bottom plate, etc.).

While a container is seated in a storage location, the flange(s) is seated on the supports 101 (e.g., the bottom plate 12 of the FOUP 2 is seated on the supports 101). If, for example, a container includes a flange extending from the top of the container, the container is hung or suspended from the supports 101 by the flange seated on the supports 101. By way of example only, a flange may comprise a horizontal, angled or stepped surface, a series of pins or rods extending from the container shell, and so on. Similarly, the supports 101 may comprise any structure for supporting the container's flange features. If, for example, a conventional FOUP is seated in a storage location, the supports 101 and the FOUP flange preferably mate such that the workpieces stored in the FOUP are substantially horizontal while the FOUP is seated in the storage location. Of course, the workpieces stored in a container may be oriented in any position in the container while the container is seated in a storage location (e.g., vertical, angled, etc.). For purposes of describing this invention only, the stocker 100 will be described in operation with containers including a bottom plate and corresponding supports for supporting the container substantially horizontal.

In the case where the bottom support plate of a large capacity FOUP and a small capacity FOUP are the same width, the distance or pitch d4 between supports 101 may be standardized for the entire stocker 100. For example, support structures 102 and 104, which are supporting a large capacity FOUP 2 in FIG. 3, are spaced apart by a distance d4. And the support structures 118 and 120, which are supporting a small capacity FOUP 20 in FIG. 3, are separated apart by the same distance d4. By separating the support structures 101 of each storage location apart by a standard distance (e.g., distance d4), the stocker 100 may store either a large capacity FOUP 2 or a small capacity FOUP 20 in any of the storage locations. Of course, the distance between each set of supports 101 does not have to be equal.

The stocker 100 shown in FIG. 3 comprises four columns, each column having eight storage locations: a first storage column C1, a second storage column C2, a third storage column C3 and a fourth storage column C4. FIG. 3 illustrates that the total storage capacity of the stocker 100 depends on the number of small and large capacity FOUPs stored in the stocker 100. Here, the first column C1 stores a small capacity FOUP 20 in each of the eight storage locations. The second column C2 stores one large capacity FOUP 2 and six small capacity FOUPs 20. The large capacity FOUP 2 essentially takes up two storage locations (the top two storage locations in columns C2). Thus, column 2 only stores seven FOUPs. The third column C3 stores three large capacity FOUPs 2 and two small capacity FOUPs 20. The fourth column C4 stores four large capacity FOUPs 2.

The stocker 100 shown in FIG. 3 is storing twenty-four FOUPs. If the stocker 100 stored all small capacity FOUPs 20, the stocker 100 would store thirty-two FOUPs. In contrast, the stocker 10 shown in FIG. 1 may only store a maximum of sixteen FOUPs, regardless of what combination of small capacity and large capacity FOUPs were stored in the stocker 10.

The stocker 100, as shown in FIG. 3, stores two different sizes of containers: large capacity FOUPs 2 and small capacity FOUPs 20. However, the stocker 100 may store more than two different sizes of FOUPs. To maximize the flexibility of the stocker 100, the vertical pitch d5 between the supports 101 in each storage location is preferably set by the height of the smallest container size that will be stored in the stocker 100 (e.g., height h2 of a small capacity FOUP 20). Thus, if one column of the stocker 100 stores all small capacity FOUPs, the gap g (see FIG. 4B) is minimized.

The support structure 101 may comprise many different structures. In one embodiment, each support structure 101 consists of a support bar, and each pair of supports 101 are set apart at a horizontal pitch or distance d4. The pitch d4 between support structures 101 comprises a distance that provides maximum storage of the small capacity FOUPs 20 without wasted space within the stocker 100. The pitch d4 is also determined, in part, by the width of the bottom plate or flange on each FOUP. By standardizing the width of the bottom plate or flange on each FOUP, the pitch d4 may also be standardized.

FIG. 3 illustrates a stocker 100 with a standardized pitch d4. In the FIG. 3 embodiment, the pitch d4 between the support structure 102 and support structure 104 is the same as the pitch or distance between the support structure 110 and the support structure 112, which is the same as the pitch d4 between the support structure 118 and the support structure 120 and so on. To minimize the footprint of the stocker 100, each set of supports 101 within a particular row are placed close to each other. For example, the support 118 of the set of supports 118 and 120 is placed close to the support 132 of the adjacent set of supports 134 and 132.

Each support structure 101 is also separated or set apart vertically by a distance d5 from another support 101. FIG. 3 illustrates that support structure 104 and support structure 108 are separated vertically by a distance d5. Support structure 102 and support structure 106 are separated by distance d5. Support structure 112 and support structure 116 are separated by distance d5. Support structure 110 and support structure 114 are separated by distance d5. And so on. The distance d5 is preferably greater than the height h2 of a container shell 24 of a small capacity FOUP 20. Thus, when a small capacity FOUP 20 is seated on a set of supports 101 (e.g., supports 120 and 122 as shown in FIG. 4B), a gap g exists between the top of the small capacity FOUP's container shell 24 and, in this example, the bottom plate 32 of the FOUP 20A located directly above the small capacity FOUP 20B.

FIGS. 4A-4B illustrate one embodiment of storing a small capacity FOUP 20 within the stocker 100. The small capacity FOUP 20 shown in FIGS. 4A-4B shares many common characteristics with a conventional FOUP. The small capacity FOUP 20 includes a container shell 24, a mechanically openable container door 29 that couples with the front opening 23, a top handle 26, a pair of side handles 28 and a bottom plate or flange 32. From the top view provided in FIG. 4A, the container shell 24 of the small capacity FOUP 20 has a tapered configuration. The front opening 23, in this embodiment, is substantially the same width W3 as the width of the bottom flange 32. The width W4 of the container shell 24 is narrower than the width W3 of the bottom flange 32. The container shell 24, similar to the bottom plate 32, is also tapered. FIG. 4A shows that the FOUP 20 comprises a length L2. The bottom plate 32 of the small capacity FOUP 20 is not required to extend the entire length L2 of the FOUP 20.

The large capacity FOUP 2 has similar features as the small capacity FOUP 20. The large capacity FOUP 2 includes a container shell 4, a mechanically openable door 9 that couples with the front opening 3, a top handle 6, a pair of side handles 8 and a bottom plate or flange 12. The container shell 4 and the bottom flange 32 each have a tapered configuration. The front opening 3, in this embodiment, is substantially the same width W1 as the bottom flange 32. And the width W2 of the front opening 3 is greater than the width W2 of the container shell 4.

FIG. 4A illustrates that the support structures 124 and 126 each comprise a length L1. The support structures 124 and 126 do not extend the entire length L2 of the FOUP. It is within the scope and spirit of the invention for the length of the support structures 124 and 126 to vary, and have other configurations (e.g., comprise a three-point fork structure). The supports 124 and 126 are preferably long enough to adequately support the small capacity FOUP 20. In this embodiment, the supports 124 and 126 support the FOUP by its bottom plate 32, and therefore, are long enough to support the FOUP's bottom plate 32. In other embodiments, the supports 124 and 126 may support the FOUP by the FOUP's flange (not shown) extending from the container shell (e.g., a flange extending from the top of the FOUP). If the FOUP includes a flange other than a bottom flange, the supports 124 and 126 must adequately support the FOUP by its flange. As will be discussed in more detail later, the length L1 of each support is less than the length of the FOUP (large capacity or small capacity FOUP) so that, when the FOUP is seated on a pair of supports 101, the FOUP door opening will not contact or strike the supports 101 in the storage location located above.

FIG. 4A also illustrates that, in this embodiment, the FOUP's bottom plate 32 is seated on the support surface 131 of each support 124 and 126. As mentioned above, the width W3 of the bottom plate 32 is greater than the width W4 of the FOUP shell 24. The width W3 of the bottom plate 32 may comprise any length as long as the distance d4 between supports 101 is narrower than the width W3 of the bottom plate 32. Otherwise, the FOUP 20 could not be supported by a pair of support structures 101.

Each support structure 101 may include pins (e.g., kinematic pins) or other registration or location features that would accurately engage mating features on both the large capacity FOUP's bottom plate 12 and the small capacity FOUP's bottom plate 32. These registration features would allow a FOUP to be placed on a pair of support structure 101 or in a storage location in an accurate and repeatable location. In one embodiment, the storage location may include two rounded pins on one support structure 101 (e.g., support 102) and one rounded pin on the other support structure 101 (e.g., support 104). The pair of support structures 102 and 104 would then include three corresponding registration features similar to the arrangement used for the kinematic pin alignment on 300 mm FOUPs, which are standardized by SEMI. Other alignment and/or registration features are also possible on each support structure 101. These registration features would also engage a flange extending from the FOUP if the FOUP was, for example, seated in a storage location by its flange.

FIG. 4B illustrates two small capacity FOUPs 20A and 20B seated in two vertically adjacent storage locations. Small capacity FOUP 20A is seated in the stocker 100 in a first storage location having support structures 124 and 126. Small capacity FOUP 20B is seated below the small capacity FOUP 20A, in a second storage location, on support structures 120 and 122. Both sets of support structures are horizontally spaced apart a distance d4 and are spaced vertically apart by a distance d5. The height h2 of the small capacity FOUP 20B is less than the distance d5, creating a gap g between the top handle 26 of the small capacity FOUP 20B and the bottom plate 32 of the small capacity FOUP 20A seated above. The gap g provides an area whereby a robotic arm or other FOUP transfer device may operate within, for example, to grip the top handle 26 of the small capacity FOUP 20B. Such a mechanism is well known in the semiconductor art and does not require further disclosure herein. One example of such a mechanism is disclosed in U.S. Pat. No. 6,579,052, which is assigned to Asyst Technologies, Inc., and is incorporated herein by reference. Other types of mechanisms are within the scope and spirit of the present invention. If the robotic arm or FOUP transfer device engages and/or lifts the FOUP 20B by the FOUP's bottom plate 32 or side handles 28, the gap g provides room to lift the FOUP 20B off the supports 120 and 122 and not contact the bottom plate 32 of the FOUP 20A stored above.

FIG. 4B illustrates that each support structure 101 may also include a feature to limit the lateral motion of the FOUP while the FOUP is seated in the storage location. For example, FIG. 4B illustrates that support structures 120 and 122 each contain an inclined inner wall 130 to prevent the FOUP 20B from moving laterally within the storage location. The same is true for the supports 124 and 126. Each support structure 101 may also include a similar feature or wall at the front and/or rear of the support structure 101 (not shown) to limit the forward and backwards motion of a FOUP seated on a pair of support structures 101. If the support structures 101 did include front and rear walls, the front and rear vertical walls would preferably not be excessively tall because the FOUP must be lifted over one of the walls to be placed on the set of support structures 101, increasing overhead clearance requirements (e.g., increasing the minimum required height for gap g).

FIGS. 4-5 illustrate that each FOUP contains a pair of side handles protruding from the side of the FOUP. The large capacity FOUP 2 includes a pair of side handles 8. The small capacity FOUP 20 includes a pair of side handles 28. The side handles 8 on the large capacity FOUP 2 are preferably lower than the side handles on a conventional FOUP (e.g., located towards the bottom of the FOUP shell). This way, the side handles 8 of a large capacity FOUP 2, when the FOUP is seated in a storage location, clears (does not contact) the set of supports 101 in the storage location located directly above. The stocker 100 may store conventional 300 mm FOUPs. In that case, the vertical pitch d5 between support structures 101 would be greater than shown in FIGS. 3-5 because the side handles of a conventional 300 mm FOUP are located higher along the FOUP's side wall (e.g., higher on the FOUP than shown in FIG. 3).

One or more support structures 101 in each storage location may include a sensor to determine if, for example, a FOUP is seated in the storage location. This feature may be useful to prevent any type of placement or collision errors even though the robot or transfer device that moves FOUPs between storage locations may be recording which storage locations are currently occupied. A sensor on each support structure 101 could provide a cross check or confirm that the transfer device is accurately recording this information. The transfer device may also include sensors that sense the bottom placement of the container and the containers height to cross check the stored placement information and assure that the container is gripped at the correct level or that a position (or positions) is unoccupied.

FIG. 5A illustrates that the large capacity FOUP 2 includes, among other things, a FOUP shell 4, a top handle 6, a pair of side handles 8, a FOUP door 10 and a bottom flange or plate 12. The FOUP shell 4 comprises a width W2 and a height h1. The width W1 of the bottom plate 12 is preferably greater than the width W2 of the FOUP shell 4. The depth of the bottom plate 12 may be any length as long as the bottom plate 12 adequately supports the FOUP 2 (e.g., the FOUP 2 will not tip over when seated on the supports 102 and 104). As previously discussed above, it is also within the scope of the invention for the FOUP to not include a bottom support plate and instead include a flange (not shown) extending from the container shell. If the FOUP has, for example, a top flange, the FOUP flange would be seated on the supports in a storage location.

FIG. 5B illustrates a large capacity FOUP 2 seated in a storage location of the stocker 100 on support structures 102 and 104. The height h1 of the large capacity FOUP 2 is greater than the vertical pitch d5 between the support structures 102 and 106 and the supports 104 and 108. The width W2 of the FOUP shell 4 is preferably smaller than the horizontal pitch d4 between support structures 101. FIG. 5B illustrates that container shell 4 of the large capacity FOUP 2, when the FOUP 2 is seated on the supports 102 and 104, extends between the supports 106 and 108 and does not contact either support 106 or 108. Thus, the container shell 4 extends between the supports 106 and 108, leaving a small gap between the container shell 4 and each support. Similar to the small capacity FOUPs stored in the stocker 100, a gap or empty space g is preferably located between the top of the FOUP shell 4 and the bottom plate 11 of the FOUP (small or large capacity) seated above. The gap g allows a transfer mechanism to engage the FOUP handle 6 and lift the FOUP 2 off the support structures 102 and 104. The FOUP 2 must be lifted high enough so that the bottom plate 12 clears the top of the supports 102 and 104. At the same time, the distance between the top of the side handles 8 of a seated FOUP and the supports 106 and 108 must be large enough to allow the FOUP to be lifted off the supports 102 and 104 and not strike the side handles 8 against supports 106 and 108.

FIGS. 6A-6B illustrate another embodiment of a large capacity container 50 seated in a storage location. The container 50 includes a container shell 52, a flange 54, a top handle 62 and a pair of side handles 62. In this embodiment, the container shell 52 comprises a uniform width W5. FIG. 6B shows the container 50 with both a front opening door 56 and a bottom opening door 58 to illustrate that the storage location is suitable for any type of container. The container shell 52 comprises a height h3 and a width W5. The flange 54 bottom flange, has a width W4. The flange 54 may comprise any width as long as the width W4 of the flange 54 is greater than the pitch d4 between support 101. Similar to the small-capacity and large-capacity FOUPs described above, the container 50 may include a flange 54 extending from the container shell 52 at any elevation.

FIG. 6A illustrates that the width W4 of the flange 54 is preferably greater than the width W5 of the container shell 52. The depth of the flange 54 may be any length as long as the flange 54 adequately supports the container 50 (e.g., the container 50 will not tip over when seated on the supports 102 and 104).

FIG. 6B illustrates the container 50 seated in a storage location of the stocker 100 on supports 102 and 104. Similar to the large capacity FOUP 2, the height h3 of the container 50 is greater than the vertical pitch d5 between the support structures 102 and 106 and the supports 104 and 108. The width W5 of the container shell 52 is preferably smaller than the horizontal pitch d4 between supports 106 and 108. FIG. 6B illustrates that container shell 52 of the container 50, when the container 50 is seated on the supports 102 and 104, extends between the supports 106 and 108 and does not contact either support 106 or 108. Thus, the container shell 52 extends between the supports 106 and 108, leaving a small gap between the container shell 52 and each support. In a preferred embodiment, the pitch d5 between supports 101 is greater than the height h3 of the container shell 52. This way, a gap or empty space (not shown) is vreated between the top of the container shell 52 and the flange 54 of the container seated directly above. The gap allows a transfer mechanism to engage the container handle 60 and lift the container 50 off the supports 102 and 104. The container 50 must be lifted high enough so that the flange 54 clears the top of the supports 102 and 104.

It should be appreciated that the above-described stocker 100 and methods for storing and transporting FOUPs within the stocker 100 are for explanatory purposes only and that the invention is not limited thereby. Having thus described a preferred embodiment of a method and system for storing FOUPs, it should be apparent to those skilled in the art that certain advantages of the within system have been achieved. It should also be appreciated that various modifications, adaptations, and alternative embodiments thereof may be made within the scope and spirit of the present invention. For example, the stocker 100 may also be used in connection with other equipment within in a semiconductor fabrication facility, and it should be apparent that many of the inventive concepts described above would be equally applicable to the use of other non-semiconductor manufacturing applications. 

1. A container storage device for storing large capacity workpiece containers and small capacity workpiece containers, each small capacity workpiece container and large capacity workpiece container includes a container shell and a flange, the container storage device comprising: a first storage location for supporting a workpiece container by its flange, said first storage location having a first support spaced apart from a second support by a predetermined distance that is greater than the width of a container shell of a large capacity workpiece container; and a second storage location for supporting the flange of a workpiece container, located above said first storage location, including a first support spaced apart from a second support by a predetermined distance that is greater than the width of a container shell of a large capacity workpiece container; wherein the vertical pitch between said first and second supports of said first storage location and said first and second supports of said second storage location is less than the height of the container shell of a large capacity workpiece container.
 2. The container storage device as recited in claim 1, wherein said first support and said second support of said first storage location each include a registration feature for engaging the flange of either a large capacity workpiece container or the flange of a small capacity workpiece container.
 3. The container storage device as recited in claim 1, wherein said first support and said second support of said second storage location each include a registration feature for engaging the flange of either a large capacity workpiece container or the flange of a small capacity workpiece container.
 4. The container storage device as recited in claim 1, wherein said first support and said second support of said first storage location restrict the lateral movement of a workpiece container seated on said first and second supports of said first storage location.
 5. The container storage device as recited in claim 1, wherein said first support and said second support of said second storage location restrict the lateral movement of a workpiece container seated on said first and second supports of said second storage location.
 6. The container storage device as recited in claim 1, wherein said first storage location includes a sensor to determine whether a workpiece container is located in said first storage location.
 7. The container storage device as recited in claim 1, wherein said second storage location includes a sensor to determine whether a workpiece container is located in said second storage location.
 8. A container storage device for storing large capacity workpiece containers and small capacity workpiece containers, each small capacity and large capacity workpiece container including a container shell and a flange, the container storage device comprising: a first storage location including a first support and a second support horizontally spaced apart from each other by a predetermined distance, said predetermined distance being greater than the width of a container shell of a large capacity workpiece container yet able to support a workpiece container by its flange; a second storage location, located above said first storage location, including a first support and a second support horizontally spaced apart from each other by a predetermined distance, said predetermined distance being greater than the width of a container shell of a large capacity workpiece container yet able to support a workpiece container by its flange; wherein when a large capacity workpiece container is located in said first storage location, the container shell of the large capacity workpiece container extends between said first support and said second support of said second storage location.
 9. The container storage device as recited in claim 8, wherein said first support and said second support of said first storage location each include a registration feature for engaging the flange of either the large capacity workpiece container or the flange of the small capacity workpiece container.
 10. The container storage device as recited in claim 8, wherein said first support and said second support of said second storage shelf each include a registration feature for engaging the flange of either the large capacity workpiece container or the flange of the small capacity workpiece container.
 11. The container storage device as recited in claim 8, wherein said first support and said second support of said first storage location restrict the lateral movement of a workpiece container seated in said first storage location.
 12. The container storage device as recited in claim 8, wherein said first support and said second support of said second storage location restrict the lateral movement of a workpiece container seated in said second storage location.
 13. The container storage device as recited in claim 8, wherein said first storage location includes a sensor to determine whether a workpiece container is seated in said first storage location.
 14. The container storage device as recited in claim 8, wherein said second storage location includes a sensor to determine whether a workpiece container is seated in said second storage location. 